The production of granulocytes and macrophages from primary cultures of hematopoietic cells will be investigated in vitro. Clonal soft agar methodologies which detect the specific proliferation of committed myeloid stem cells (CFU-c) in response to humoral growth stimulatory glycoproteins termed colony stimulating factor(s) (CSF(s)) will be utilized. Bone marrow and peripheral blood cells from a large number of patients with leukemia, myeloproliferative disorders, and Hodgkin's disease will be analyzed at diagnosis and during therapy for their capacity to both elaborate and respond to recently defined specific inhibitory regulatory molecules, Prostaglandin E and Lactoferrin. Biophysical cell separatory techniques will be employed to investigate heterogeneity amongst myeloid cell populations which respond to, (CFU-c), or elaborate, (macrophages/monocytes, neutrophils), stimulatory and inhibitory regulatory molecules. Site(s), mechanism(s) of action and physiological significance of specific feedback regulation in the development and progression of acute and chronic myeloid leukemias and myelodysplastic diseases will be determined.